Page 110 - Understanding Flight

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4
CHAPTER

Stability and Control

ne of the greatest improvements in aircraft over the last few
decades has been in the area of stability and control, which is dis-
Ocussed in this chapter. Stability is the tendency of an airplane to
return to a previous condition if upset by a disturbance, such as a gust
or turbulence. Control is the ability to command the airplane to per-
form a specific maneuver or to maintain or change its conditions.
Before WWII stability and control did not receive much
emphasis. The issue was merely how well the pilot thought the
airplane “handled.” Different philosophies reigned. For example,
the Wright brothers felt that a less stable airplane was better
because they believed it forced the pilot to be diligent. The Wrights’
competitor, Glenn Curtiss, believed that an airplane should be very
stable to reduce the pilot’s workload. The Curtiss camp prevailed in
the long run.
After WWII, engineers started to develop quantitative means for
determining airplane stability and handling properties. Today the
computer can do the work of controlling the unstable airplane while
the pilot focuses on other tasks. In these next few sections we guide
you through some basic principles of stability and control.

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